Papermaking process utilizing modified locust bean gum



Patented July 7, 1953 PAPERMAKING PROCESS UTILIZING MODI- FIED LOCUST BEAN GUM f Nat Frisch, White Plains, and Frank J. Sweeney, Forest Hills, N. Y., assignors to Stein, Hall 85 Company, Inc., New York, N. Y.,- a corporation of New York No Drawing. OriginaI application December 16, 1948', Serial No. 65,717. Divided and this application June 26, 1951, Serial No. 233,697

3 Claims.

The present invention relates to an improvement in the process of making paper.

This application i a division of. application Serial No. 65,717, filed December 16, 1948.

Many attempts have been made in the past to speed up the paper making process and to increas the strength of the paper formed thereby. Thus, for example, it has been proposed to incorporate into the paper stock locust bean gum or flour prepared from the seed endosperm of the locust or carob tree (Ceratom'a siliqua), a perennial legume native to the Mediterranean region. The fruit of this tree is in the form of pods. It was known to the ancients as manna and in later periods has been known as St. J ohns bread. The gum lpowder generally known as locust bean gum is obtained from the seeds in these pods and has been utilized heretofore. as a film forming material in textile sizing and as a thickening agent in printing and dyeing.

It is known that the addition of locust bean gum to paper stock will result in paper having improved wet and dry strength characteristics. The use of locust bean. gum in the manufacture of paper has, however, been discouraged due to the, considerable diflicultyinvolved 'in uniformly distributing the locust bean gum throughout the aqueous furnish. Even when special equipment in the form of injectors and high speed stirrers is used and the locust bean gum is added slowly to water, an appreciable proportion of the locust bean' gum will remain in the form of lumps even after cooking. If these lumps get intolthe sheet they cause fisheyes and later causes breakdown the sheet. Specialfequipment must therefore be utilized ,tostrain out theselumps;

which incidentally result in a waste of lo'cust bean gum, and the tanks in which the gum is mixed and cooked must frequently b'e drained and cleaned. The additional equipment required and the precautions that must befollowed in order to incorporate locust bean gum .in paper stock have substantially'ofiset the advantages ob-' tained by use of the gum with the result that the use of locust bean gumin the. paper industry has not become widespread. g

It has now been found that conventional paper making operations can be materially improved by adding to the aqueous suspension of fibers, normally referred to as the furnish; at a point after all operations designed vto substantially modify the fibrous constituents by mechanical means are completed andprior to the formation of the web, i. e., preferably at the head box, fan :pump or stock regulator box, an aqueous solu- 2 tion of a combination of locust bean gum, a sodium borate and an acid material selected from the group consisting of glyoxal, pyruvic aldehyde,

ammonium chloride, citric acid, boric acid and aluminum sulfate prepared preferably by the cooking operations subsequently disclosed. This method avoids the difiiculties involved in adding straight locust bean gum to the furnish, significantly improves the paper making processand results in improving the characteristics of the paper produced thereby.

The aqueous solution of a combination of locust bean gum, borate and an acid material can be prepared with utmost facility in any one of a number of ways. A dry mixture of locust bean gum, borat and acid material may be dispersed readily in cold water or a dry mixture of locust bean gum and borate may first be dispersed in cold Water and the acid material added to the aqueous dispersion so formed. Neither of these methods results in the formation of objectionable lumps and the complete dispersion of the materials can be accomplished in a matter of seconds. The dispersion is then cooked at an elevated temperature of the order of about 165 F. to 212 F., preferably about 200 F. "to open,

swell or gelatinize the locust bean gum and thereby form a' clear and viscous aqueous solution.

' Tests have shown that ina sheetinto which this material has been incorporatedan improvement information results, and also that the addition of the material of thisinvention results in a general, improvement'in the quality of paper produced from a given stock. The utilization of this invention, for example, has made it possible to increase the capacity of a mill havinglimitedj drying facilities without reduction in salient properties by making it possible'to use stock of increased freeness thereby permitting a greater amount of water to drain from the web during passage over the wire prior to drying. Also the capacity of a mill to produce a uniformly'goodquality paper has been increased in view of the improved web'formation from mediocre or poor stock. Thus, for exa'mp le, it has been found that the method of 'adding a combinationof locust bean gum, borate and acid material to the furnish makes it possible to reduce the proportion of rela tively expensive sulfitepulp and increase the proportion of relatively inexpensive groundwood without deleteriously affecting the characteristics of the paper produced thereby or slowing down the speed of the web. Normally such standard finalquality could be obtained only by a relatively has been found that optimum results are obtained by maintaining the pH at about 8.0 to 8.2. Within this more limited range, the locust bean gum will become gelatini'zed quite readily and the viscosity of'the cooked solution is sufficiently low.

to permit easy transference of the cooked .solution from a supply source to the head box, stock regulatorbox, fanpump or to any other point erable effect upon the results obtained in so far as.

handling and dispersibility are concerned Asthe proportion of locust bean gum inthe combination is decreased, the ease with which it can be dispersed in water is increased. On the other hand, as the proportion of locust bean gum in the combination approaches 100%, it becomes more difficult to disperse in water and more liable to form lumps that must be strained out prior to the addition of the solution to the furnish. As a practical matter, the presence of less than about 50% locust bean gum in the combination is too little to obtain the full; benefits derived from its use and the presence of more than about 96% of the gum will result in suflicient dispersing difficulties to make its use uneconomical. It is generally preferred therefore to limit the proportion of locust bean gum in the combination to between about 65% and 93%. Optimum results have been obtained with concentrations of between 85 and 90%.

Changes in the relative proportions of borate and acid material also have a considerable efiect upon the results obtained in the paper making operation and moreparticularly' upon the consistency and characteristics in the aqueous solution formed when the combination is added to water and cooked. The borate tends to impart to the cooked solution a heavy body, high film strength and stringiness. The acid material reduces the ropiness" of the cooked solution, imparts a long stringy character thereto and reduces its viscosity to. a. level that makes handling of the-solution practicable,

It, has generally been. found desirable to adjust the, relative proportions of locust bean gum, borate and acid material so that the dispersion thereof in water before cooking or the solution thereof after. cooking will have a pH between about.3 and L0. The lower limit ofthe pH range is. determined by the characteristics. of the particular locustbean gum in the. combination and particularly by its ability to open or. become gelatinized. when. cooked. If the pH is reduced to a. value, below about 3;, it, becomes extremely difiicult, and in some cases impossible, to gelatinize, the locust bean gum by cooking. The. upper limit of the pH range is determined by the viscosity of, the cooked solution. It is essential, in practice that the cooked solution be not so viscous that it cannot. readily be transferred from a cooking vessel to a supply vessel or from a supply vessel to the head box, fan pumpor stock regulator box. Reduction of the viscosity simply by diluting the solution with water is not practicable because that would involve increasing the capacity of the cooking vessel or supply tank and of" the pumping equipment utilized to add the cooked solution to the furnish. It. is preferable therefore to maintain the pH between about 3 and10'so that the cooked solution will not be too viscous'and at the sametimenot too acid to prevent or inhibit gelatinization of the locust bean gum; While'it is possible to'carry out the process of this invention" at either' extreme pH value, it

at which the'com'bination is added to the furnish. Satisfactory viscosity and gelatinization conditions are normally obtained by maintainin the 7 ratio. of borate to acid material at between about l-:l and- 311; and preferably at about 2:1.

A mixture that has been found to be particularly successful is one containing 85% by Weight of locust bean gum, 10% by weight of borate and 5%. by weight of acid material. When a handful of thismixture is simply dumped into cold water, it at first floats on the surface. Within a few seconds, however, the mass of material breaks up into smaller portions which fall to the bottom until all of it has left the surface of the water. Simple stirring of the water will thereupon form a uniform dispersionof the material which, upon being cooked to a temperature of about 200 F., will form a viscous, stringy'and transparent solution.

By way of contrast; when straight locust bean gum is dumped into cold water, only a small portion of it may fall to the bottom and most of the locust bean gum remains floating on the surface. The outer portions of the mass apparently absorb water, swell and become sticky so as to form a coating that denies access of water to the interior of the mass. Vigorous stirring fails to produce a uniform distribution of the gum throughout" the water and cooking thereof at'200" F. results in a syrupy mass containinglumps which must be removed before it:can be added to the furnish;

When it is desired tq, employ'mixtureshaving concentrations of locust bean gum that are less than about starch may be added to-make up for the lack of locust bean gum. Thus; forexample, favorable results have been obtained with a mixture consistingj'of 68%, locust bean gum, 17% starch, 10% borate and" 5% acid; material. Small amounts" of oxidizing agents, such as barium peroxide and sodium perborate may be added to thin out the solution prepared when the combination is dissolvedin water. I

The borate maybe anyjsuitableboratesuch as,

for example, sodium tetraborate' (borax) and sodium metaborate.

The acid material "may. be glyoxali pyruvic aldehyde. ammonium chloride; citric 'aci'dgboric acid or aluminum sulfate oraicombination clone or more. of said materials... The. presence of glyoxal or amnioniumbhiloride. inLtheicombinaftion. is; particularly -desirable because they b'oth promote; an extremely rapid and facile dispersion of the mixture inzcoldwater. A- mixtureconsist ing of"% locust beangum-,jl0 borax and 5%.

glyoxal, for example, will readily and completely disperse in: water at. room. temperature in. as little as 7 seconds. If ammoniumachloride isused instead of the glyoxal, the mixture will disperse under the sameconditions and 'inthe same manner-in as little as:9;6 seconds. Glyoxal therefore is preferable from the' standpoint ofrapidity of dispersion whereas ammonium chloride is preferable: fromthe standpointof' economy inasmuch as the price of ammoniumchloride ismuch lower than that of glyoxali 7 Aqueous" solutions containing from about- A;

the head box, at the fan pump or in the regulator box at a rate sufiicient to add from about 1 to or 30 lbs. of the mixture, based on the dry weight thereof, to a ton of furnish, likewise'based on the dry weight thereof. As in ordinary paper making processes, the concentrated stock, consisting of a 15 a maximum of approximately 4% solids, is diluted at the fan pump to a much more dilute state, e. g., 0.5%.

The addition of a solution of lucust bean gum, borate and acid material to a paper stock permits increasing the freeness of the stock, reducing the power consumption in the refining phases and the steam consumption in the dryer section, all of which makes possible an increase in the speed at which the paper is run oil, and generally improves the characteristics of the paper producedat a given set of machine conditions.

A number of typical formulae are listed in the tables below, the numerals therein referring to tory scale, corresponding to the number of solu-' tions prepared, were then made. In each run, one of the prepared solutions was added to the furnish at a rate of 10 lbs., based on the dry weight, of solution to a ton of furnish, likewise based on the dry weight.

; Two sheets each having a weight of 2.8 grams were selected from each run to eliminate test errors due to variations in the weight of the sheets produced and each sheet selected was subjected to ten Mullen tests. The averages of the twenty Mullen tests in'each run are tabulated below: 7 r 7 Formula No.

4 Locust Bean Gum Alone Eacumtple 2 Dry mixtures corresponding to formulae Nos. '7, 8, 9, 10, 11, 13, 14, 16, 18, 19 and 20 were made up, on a laboratory scale into 1% aqueous solutions by dispersing one part by weight of each dry mixture in about 50 parts by weight of water,

- Barium Peroxide. 1

percentages by weight. cooking the resulting dispersions to 200 F. and

TABLE 1 Formula No l 2 3 4 5 6 v 7 8 9 10 11 Locust Bean Gum 85 87 90 90 85 85 S0 70 60 84 Borax 10 7 5 6 10 10 12 20 26. 6 33. 3 11 Glyoxal. 5 6 5 4 5 5 5 5 Pyruvic Aldeh Ammonium Chloride 5 5 8. 4 11.7 3

TABLE 2' Formula No 12' 13 14 15 16 17 18 19 21 Locust Bean Gum Powdered Potato Stare Borax Sodium Metaborate- Glyoxal Citric Acid Bon'c Acid- I Aluminum Sulfate" 5 Sodium Perborate "Dowicide A In order to further illustrate the invention without, however, intending to limit its scope thereto, the following examples are included.

then adding sufficient additional water to bring the concentration of solids down to 1% by weight. The temperature of these solutions was main- 0 Example 1 tained at about 180 F,

A number of paper making runs on a labora-,

Four batches of locust bean gum, borax and glyoxal, corresponding to formulae Nos. -1, 2, 3 and 4 of Table 1, were made up on a laboratory scale. A 1% aqueous solution of each batch was formed by dispersing one part by, weight of the dry mixture in about 50 parts by weight of water, cooking the resulting dispersion to 200 F. and then adding sufiicient additional water to bring the concentration of solids down to 1% by weight.

The temperature of these solutions was maintained at about 180 F.

A 1% solution of locust bean gum alone was prepared in a similar manner.

A number of paper making runs, on a laboratory scale were then made. In each run, a number of blank and modified paper sheets were made. The blank sheets were made without adding a locust. bean gum containing solution to the furnish and the modified sheets were made by adding one of the prepared solutions at a rate of 10 lbs., based on the dry weight, of solution to a 1:" tests conductedon each set of two sheets are tabulated-below r Blank It is to be understood that innumerable modifications will readily occur to those skilled in the art upon reading thisdescription. All such modifications are intended to be included within the scope of the, present invention asjdefined' in the appended claims.

We claim 1. In a process of making paper from an aqueous suspension of fibrous material, the step which comprises adding, to said suspension, after all operations designed to substantially modify the fibrous constituents by mechanical means are completed andprior to the formation of the web, an aqueous solution of a cooked mixture of locust bean gum-, asodiumborateand citric acid, the gum being presentin the mixture in an amount from at least about equal to the combined weight of borate and acid to about 96% of the mixture, the relative proportions of the borate to the acid ranging from about 3: 1 to 1:1 by weight, and the amount of cooked mixture of gum, borate and acid in the solution ranging from an appreciable amount up to about 30 lbs. per ton of fibrous material in the aqueous suspension, both based on the dry weight thereof. ';j

2. In a process of making paper fromv an aqueous suspension of fibrous material, the step which comprises adding, to said suspension, after all operations designed to substantially modify the fibrous constituents by mechanical means are completed and prior to the formation of the web,

an aqueous solution of a cooked mixture conta-ining from to 96 parts by weight of locust bean" gum, from 2 to 35 parts by weight of a sodium borate and from 1 to 20 parts by Weight o'f.citric"6 8i acid-, the amoiiiit er Fe okedimixture -61: gum; borate and acid in the solution rangihg1from1 an appreciable amount up to about. 30 lbs. per. ton offibrous 'niat erialiin -the .ao ueous suspension, both based on-the-dry-weight thereof.

3. In a' process .of-makin'g paper from an 'aqueous' suspension oi fibrous material, the step which comprises "adding-, to'. "said'lsuspension, after all operations designed ta-substanti-ally modify the nitrous constituent mechanical means are complete'cljand priorto th fo rmation 6f the web, an aqueous solution ofa cooked mixture containing from to pa'rts by' weight of locust bean gunn'fromj 5 .to 1-0 parts' 'b y weight of: a. sodium.

borate and from 2110 6 parts byweight of citric acid; thelam'ount' -of,..cooked mixture of gum,

borate and acidin' the solution ranging from an appreciable amount up to about 30 lbs." per ton" of; fibrous'materiai in the aqueous suspension, both basedflon' 'the-dryweight'thereoi v v narnaxscn.

l j J. SWEENEY.

Reterences Cited in the file of this patent 7 UNI'IED' STATES PATENTS V,

" K Date" Number Name 7 60,635 Irving et al Dec. 18, 1866 1,106,335 Pinel Aug. 4, 1914 1,280,861 Satow Oct. 8, 1918 1,335,356 Dunham Mar. 23, 1920 1,448,847 Kaiser Mar. 20, 1923 1,839,346 Seferiad is Jan. 5, 1932 2,144,522 Braun June 17, 1939 2,258,628 Smith Oct. 14,1941 2,336,367 Osborne 1- Dec. '7, 1943 Q FOREIGN PATENTS Number Country I Date 508,135 7 Great Britain -1; June"27,'1'939 OTHER. REFERENCES Broadbent et al TechSupplement to Worlds Paper Trade, Review-June 2'7, 1941, pp. 49-56.

Mason, Chemical Industries, Jan. 1944, pp. 66 and 67, r

. I he Determination of Hydrogen Ionby Clark,

- published by Williamsand Wilkins 00., Baltimore,

Md (192 Chapter 6, particularly pp, 10 .1 1 and 1 1 2'- 117 1' p 1 V. V. 

3. IN A PROCESS OF MAKING PAPER FROM AN AQUEOUS SUSPENSION OF FIBROUS MATERIAL, THE STEP WHICH COMPRISES ADDING, TO SAID SUSPENSION, AFTER ALL OPERATIONS DESIGNED TO SUBSTANTIALLY MODIFY THE FIBROUS CONSTITUENTS BY MECHANICAL MEANS ARE COMPLETED AND PRIOR TO THE FORMATION OF THE WEB, AN AQUEOUS SOLUTION OF A COOKED MIXTURE CONTAINING FROM 85 TO 90 PARTS BY WEIGHT OF LOCUST BEAN FUM, FROM 5 TO 10 PARTS BY WEIGHT OF A SODIUM BORATE AND FROM 2 TO 6 PARTS BY WEIGHT OF CITRIC ACID, THE AMOUNT OF COOKED MIXTURE OF GUM, BORATE AND ACID IN THE SOLUTION RANGING FROM AN APPRECIABLE AMOUNT UP TO ABOUT 30 LBS. PER TON OF FIBROUS MATERIAL IN THE AQUEOUS SUSPENSION, BOTH BASED ON THE DRY WEIGHT THEREOF. 